Morphological and molecular differentiation of the croatian populations of Ouercus pubescens Willd. (Fagaceae)

Taxonomy of the genus Quercus L. is very complicated and often controversial because of its great variability and intense gene flow among the related species. The purpose of this research was to determine morphological and molecular variation, relationships and taxonomic status of the Croatian populations of Quercus pubescens Willd. using morphological analysis of the leaves and RAPD-PCR technique. The results of the morphological and molecular analyses were very similar, both showing differentiation of the southern (Mediterranean) from the northern (Continental) pubescent oak populations. These two groups were clearly separated and the estimated gene flow among the populations that belong to different groups (Nm=1.38) is significantly less than among the populations that belong to the same group (Nm=3.70). The obtained results were compared to the available studies. This study confirms a high variability of the Q. pubescens populations, but differences were not so big to confirm the opinion of existence of several species in this area. The conclusion is that the southern Croatian populations could be pure Q. pubescens populations, while the peculiarities of the northern Croatian populations originate probably from the Q. petraea introgression.